Return ONLY valid JSON (no markdown fences, no extra text).

You are summarizing a past OmniAgents coding session. The input contains:

• Session metadata
• A chronological transcript of message objects (raw JSON items, including tool calls/outputs when present)

Your job is to produce a structured summary that helps an AI coding agent quickly reuse the session.

JSON schema (keys must exist; use empty arrays/strings if unknown): { "session_id": "string", "project": "string", "agent": "string", "created_at": "string|null", "message_count": 0, "summary": "string", "decisions": ["string"], "constraints": ["string"], "key_files": ["string"], "commands": ["string"], "tests": ["string"], "open_questions": ["string"], "next_steps": ["string"], "notable_errors": ["string"] }

Guidelines:

• Prefer concrete, tool-verifiable details (paths, command names, identifiers).
• If the transcript includes tool outputs, extract the key results.
• Put only file paths in key_files (no prose).
• Keep summary concise but information-dense.